Patch for Bug ID-357657. Replaced QCheckbox objects named "m_AnswerMixedCheck" and "m_ReducedCheck" to QRadioButton to select only one option in displaying the type of Answer(either Mixed Fraction or Reduced form).

Testing Done

It works successfully without any bugs fulfilling the objective of the patch. QCheckBoxes under "Answer Section" replaced with QRadioButtons, changes reflected to both, MainQtWidget.h as well as MainQtWidget.cpp.